Maybe, but it happens often, I think. First quarter, 0-0, nothing particular happening, defense lines up in standard formation like they do 80% of the time and the QB audibles.
I understand why they put a guy in motion, makes sense to me.
Well, think about it. You have plays that are designed to exploit certain concepts.
Let's say the OC knows the tendencies of the opposing DC. You're in a certain down and distance where the DC likes to call cover 2 man.
So you call a play designed to beat cover 2. Let's say your X alone on the left is running a double move fly. Your Y on the right is running an in route with the slot inside him running a corner/out. And the tight end on the right side of the line is going to chip and then release down the seam. You're trying to overload the safeties by forcing two safeties to help on 3 receivers, with two outside and one up the seam. Pretty basic concept.
Your QB is coming up and he sees that 2 high defense that he wants... But he also sees the corners way laid off. And he thinks, "Oh shit, they're playing quarters (4 deep) on the back end with zone underneath! This cover 2 man beater is going to get smothered!" So he audibles.
The OC is going to know what defense he wants to see for play #1, and have a backup play that works better if the QB sees something else.
From our perspective, both defenses probably look like "base" in real time. But the QB not only knows the playcall and what it's designed to exploit, he sees the nuance in ways we're not trained to... Based on alignment, personnel, etc he can see if it looks like quarters zone vs cover 2 man, and switch into a better play.